1. Field of the Invention
The invention relates to a microphone, more particularly to a microphone that can be placed stably.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional microphone 1 is shown to include a tubular housing 11 extending along a longitudinal axis, a perforated cover 12 mounted on a front end of the housing 11 and having a circular cross section along a plane transverse to the longitudinal axis, and a positioning ring 13 sleeved on the perforated cover 12 for protection purposes and having an outer peripheral surface that is formed alternately with a plurality of rolling sections 132 and positioning facet sections 131. Each of the positioning facet sections 131 has two opposite ends 1311 connected respectively to two adjacent ones of the rolling sections 132, as shown in FIG. 2. Each positioning facet section 131 is flat, whereas each rolling section 132 is outwardly and radially convex relative to the longitudinal axis.
FIG. 3 illustrates a trace of the conventional microphone 1 when placed on a plane (L). When an external action force (F), which is composed of a horizontal component (F1) and a vertical component (F2), is applied to the conventional microphone 1, the gravity center (G) of the conventional microphone 1 tends to move along a path as indicated by an imaginary line (T). Under such a condition, a vertical reaction force (M) acts on the conventional microphone 1 as a result of the action force (F) while one of the positioning facet sections 131 contacts the plane (L). Since the horizontal component (F1) of the action force (F) results in continuous rolling of the conventional microphone 1, stable placement of the conventional microphone 1 on the plane (L) cannot be ensured.